Great to see coverage of this XSS protection - according to http://caniuse.com/contentsecuritypolicy it's supported by a wide range of browsers beyond Firefox and Chrome, including various Webkit browsers and even IE10, but not yet Opera.
While it can't help with IE9 or earlier, it does at least limit the attack surface for XSS to users on those browsers.
Posted Feb 7, 2013 20:55 UTC (Thu) by roc (subscriber, #30627)
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From caniuse: "IE 10's support is limited to the 'sandbox' directive." So it doesn't have any of the features that Francois talked about. It's basically got CSP syntax for the <iframe sandbox> feature, and none of the actual CSP features.